In the office environment of a modern society, people have to use many data processing equipments to carry out their assignments which includes video display device. With the advent of the larger size monitors, many different types of approach are provided to make the usage of heavier monitors easier and ergonomic.
For instance, the co-pending U.S. patent application Ser. No. 08/147,628, which was filed on Nov. 5, 1993 and will be assigned to the assignee of this application, discloses a direction adjustment and an angle adjustment apparatus for a video display device. The direction adjustment apparatus comprises an upper support and a lower support. The upper support has a bottom which has a plurality of cavities each of which accommodates a roller. The lower support is rotationally connected to the upper support. The lower support has at least a circular guide rail for seating and guiding the roller. The weight of the video display device is transmitted to the circular guide rail of the lower support through the upper support and the roller, and when the upper support is rotated as a result of the direction adjustment of the video display device, the roller is rolling within the circular guide rail of the lower support. The angle adjustment apparatus comprises an upper support, an angle adjustment device and a connecting device. The upper support has a top of a concave shape which has a plurality of cavities each of which accommodates a roller. The angle adjustment device has a bottom of a convex shape which is seated on the roller of the upper support and contacts with the roller in a form of rolling friction. The connecting device connects the angle adjustment device slidably with the upper support. The angle adjustment of the video display device is accomplished by adjusting the relative angular position of the angle adjustment device with respect to the upper support.
However, even with the latest state of arts, the lower (base) support still can not roll on the surface it is seated if the user intends to push the monitor to a desired location.